Light scattering from nonequilibrium concentration fluctuations in a polymer solution

Light scattering from nonequilibrium concentration fluctuations in a polymer solution

Concentration Fluctuations in a Polymer Solution under a Temperature Gradient

We have performed small-angle Rayleigh light-scattering measurements in polymer solutions under various externally applied temperature gradients. Our experiments confirm the existence of an enhancement of the concentration fluctuations. The nonequilibrium concentration fluctuations are proportional to s=Td2yk4, where =T is the applied temperature gradient, and k is the wave number of the fluctu...

Scattering from small colloidal particles in a semidilute polymer solution

The correlations between the segments of a semidilute polymer solution are found to induce correlations in the positions of small particles added to the solution. Small means a diameter much less than the polymer’s correlation length. In the presence of polymer the particles behave as if they attracted each other. It is shown how the polymer’s correlation length may be determined from a scatter...

Brillouin light-scattering from polymer gels

The experimental results of the Brillouin shift and width for poly(vinyl alcohol) and poly(vinyl chloride) gels as a function of gel network volume fraction have been analysed using the theory of Marqusee and Deutch for Brillouin light-scattering from polymer gels, incorporated with a new plausible assumption relating the speed of sound in the gel network with its volume fraction. It has been f...

INELASTIC LIGHT SCATTERING FROM THERMAL FLUCTUATIONS IN GASES by NOEL

We have studied the Brillouin spectrum of light scattered by the dilute monatomic one component gases xenon and helium and by the xenon-helium binary gas mixture. In a one component monatomic gas the scattered light spectrum for a scattering process with momentum transfer, K, and energy transfer, w, is proportional to the power spectrum, S(K, W), of fluctuations in the density of the gas. In a ...